[Heath] HP-23 power supplies - an idea and some questions.

[Bill Cromwell]

Hi,

I haven't looked for a while but some of those ratings are DC *input* to 
the plate. Later tables from the same sources list the output power. Now 
I need to look again. All three of the transmitters I have with a pair 
of 6146 tubes run much closer to 900 volts on the plates and one of them 
is even slightly over 900 volts. There have been no problems with the 
higher voltage and I run mine conservatively anyway at lower plate 
current (offsetting the higher voltage in the power equations). I do try 
to pay attention to "absolute maximum plate power dissipation". But even 
those can be 'pushed' and I have heard of 1200 volts on 6146s. Yikes.  I 
do not push the pair(s) much over about 90 watts out and more often 60 
watts or less.

Ken's proposed empirical test seems worthwhile if he wants the 
efficiency. I'm not sure that winding would see all of that DC applied 
but "ratings" and actual limits may be different in your favor. Use the 
series light bulb trick for testing just to minimize or prevent major 
smoke damage and shrapnel. Let us know how that works out. I have put 
the buck or boost winding on the primary side where the steam pressure 
is much less. In your case that raises the heater voltages as far as I 
know - assuming the transformer has all the winding in just one unit.

Put the iron you are testing under an inverted steel washtub in the back 
yard with the series light bulb outside of the tub. Stake the tub down 
at the handles. I have taken those measures when other people told me I 
could 'not do that' but the science suggested I could. I never made any 
smoke or shrapnel but I still do that for "new ideas" with potential 
unpleasant results. My next use may be for experiments with rechargeable 
lithium batteries.

73,

Bill  KU8H

On 02/04/2018 09:02 PM, Glen Zook via Heath wrote:
> Methinks you mean 3 dB instead of 1 dB with an increase from 100-watts
> to 200-watts.  However, even that increase will not be noted in most
> situations.
>
>
>
> As far as why Heath increased the voltage:  A new power transformer was
> used in the HP-23A that had dual primary windings for 120 VAC and 240
> VAC.  Since a new transformer was being used, Heath went ahead and
> increased the secondary voltage as well to increase the power on the
> HW-10X and SB-1XX slightly.  Of course, Heath was never conservative on
> the power ratings of their transmitters.  Having the slightly higher
> voltage did allow the equipment to come closer to the power ratings.
> However, it has been my experience working on a lot of Heath equipment
> that to make the power claimed by Heath involved pushing the 6146 final
> amplifier tubes often to beyond their ratings.
>
>
>
> Remember, the original 6146 and 6146A / 8298 were rated at 90-watts for
> Class "C" operation, 85-watts for AB-1 / AB-2 for SSB, and 67.5-watts
> for AM (all input ratings).  Heath pushed the tubes very hard for both
> SSB and AM operation.  Of course, back then, the 6146 was in production
> and very common.  Therefore, who worried if the tubes did not last as
> long as possible!
>
>
>
> Glen, K9STH
>
> Website: http://k9sth.net
>
>
> ------------------------------------------------------------------------
> *From:* Kenneth G. Gordon <kgordon2006 at frontier.com>
> *To:* Heath at puck.nether.net
> *Sent:* Sunday, February 4, 2018 7:35 PM
> *Subject:* Re: [Heath] HP-23 power supplies - an idea and some questions.
>
>
> You are absolutely correct, of course.
>
> In fact, in order to increase the signal level at the receiver enough to
> hear a difference, one
> must double the output power of the transmitter. 100 watts to 200 watts
> for 1 db difference
> at the receiver.
>
> 1 entire S unit (or 6 db, i.e. a power ratio of 4) increase at the
> receiver requires increasing
> transmitter output power from 100 watts to 400 watts. Then another S
> unit above that
> requires 1600 watts. No thanks.
>
> I am not concerned about power output here: to my way of thinking, the
> lower voltage simply
> "isn't right.".
>
> If it was not important, why did Heathkit change the AC voltage from 268
> to 282?
>
> Are there deleterious effects due to the lower voltage OTHER THAN power
> output? I
> suspect so.
>
> Screen-grid issues come to mind.
>
> But none of the above concerns me.
>
> So, I still have not gotten an opinion or an answer to my question: is
> it likely that the 410
> VDC across the 12.6 V winding of the added transformer is too much, or
> is it acceptable?
>
> If no one knows, I believe I'll try it to see. Empirical evidence is
> always good.
>
>
>
>
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